1. Field of the Invention
The present invention relates to a method for manufacturing an IC plastic package with a window.
2. Description of the Prior Art
In most semiconductor IC devices, the IC chip is sealed in a plastic package through resin-molding. The IC plastic package technology enables the mass production of IC devices and the automation of the IC device manufacturing process, and contributes quite effectively to the reduction of the cost of the IC device.
Such an IC plastic package is disclosed and described in detail, for example, in U.S. Pat. No. 3,611,061.
However, since a package for an IC chip having a light receiving surface, such as an EPROM or an image sensor, needs to be provided with a light receiving window, the plastic-molding technology could not have been applied to the manufacture of such an IC chip. Accordingly, it has been necessary to seal an IC chip having a light receiving surface in a ceramic package having a transparent window. However, the complex structure of the ceramic package with a window has been a significant impediment to the reduction of the manufacturing cost of the IC device.
Furthermore, a process for hermetically sealing a package body and a ceramic plate with a glass of a low melting point heated approximately at 450.degree. C. approximately in ten minutes is indispensable to manufacturing a ceramic IC package. Therefore, aluminum wires are used instead of Au wires for wiring, to obviate disconnection resulting from the alloying reaction of metal wires with the aluminum pads provided on the surface of the chip.
However, the low efficiency of bonding work for aluminum wires, as compared with that for Au wires, has been disadvantageous from the viewpoint of mass production. Accordingly, the industry has been desiring a method for mass-producing plastic IC packages with a transparent window at a reduced cost without subjecting IC chips to any high-temperature heat treatment process.